Abstract
The low temperatures and high hydrostatic pressures of the deep ocean directly affect the structure and function of all the proteins and membranes of ectotherms. The environment is thus an important selective force shaping the evolution of organisms in this extensive habitat. This chapter examines the effects of hydrostatic pressure on one important membrane-associated function, the transduction of an extracellular message into an intracellular second message. A number of approaches have been employed to identify and define at the molecular level the effects of pressure on transmembrane signaling, both on the components in isolation and on the entire functional complex. The effects of pressure have been compared in three cold-adapted species, which are common at different depths and hence experience different pressure regimes. These teleost species have been useful models for studies of pressure adaptation. The membrane system studied, the A1 adenosine receptor was chosen as a representative G protein-coupled receptor and because of its occurrence in teleost brain and the range of pharmacological tools available for its study.